Voice coil motor

ABSTRACT

The VCM according to an exemplary embodiment of the present disclosure includes a base unit, a mover including a bobbin arranged at an upper surface of the base unit and formed with a plurality of rotation prevention units along a periphery and a first driving unit arranged at a periphery of the bobbin, a stator including a yoke configured to the base unit to surround the mover and inner yoke units each extended to between the rotation prevention units, and a second driving unit oppositely arranged to the first driving unit, and an elastic member elastically supporting the mover, wherein an object occurrence preventing portion is formed between the rotation prevention unit and the inner yoke units to decrease a contact area between the rotation prevention unit and the inner yoke units.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a U.S National Stage Application under 35 U.S.C.§371 of PCT Application No. PCT/KR2013/005624, filed Jun. 26, 2013,which claims priority to Korean Patent Application No. 10-2012-0097323,filed Sep. 3, 2012, whose entire disclosures are hereby incorporated byreference.

TECHNICAL FIELD

The teachings in accordance with exemplary and non-limiting embodimentsof this disclosure relate generally to a VCM.

BACKGROUND ART

Recently, mobile communication devices such as mobile phones, gamemachines and tablet PCs are mounted with camera modules including imagesensors capable of storing an object in a digital still image or a videoimage.

A conventional camera module suffers from disadvantages in that that itis difficult to adjust a gap between an image sensor and a lens arrangedat a front surface of the image sensor, and it is also difficult toaccurately adjust a focus on an object, resulting in an image qualitydegradation of the digital image or video.

Concomitant with a recent development of a VCM (Voice Coil Motor), a gapbetween a lens and an image sensor can be adjusted to obtain anexcellent digital image or a video. In order to drive a VCM, the VCMincludes a stator including a magnet an a yoke, a rotor including a coilblock arranged inside the stator and arranged at a periphery of a bobbinmounted with a lens to generate an electromagnetic force in response toa driving current applied from an outside, and a cover arranged at thestator to cover the rotor.

The conventional VCM however suffers from disadvantages in that,although a portion of a bobbin is hitched at a yoke to prevent thebobbin from rotating abnormally, the bobbin contacted to the yoke allowsthe bobbin to generate particles such as fine dust or fine objects, andthe fine objects are in turn collected at an IR (Infrared) filterarranged at a bottom surface of the bobbin to deteriorate a displayquality of an image or a video.

DISCLOSURE Technical Problem

The present disclosure is to provide a VCM configured to decrease orinhibit generation of objects from a bobbin in a case a yoke and thebobbin are contacted, whereby a display quality degradation of an imageor a video can be prevented.

Technical problems to be solved by the present disclosure are notrestricted to the above-mentioned descriptions, and any other technicalproblems not mentioned so far will be clearly appreciated from thefollowing description by skilled in the art.

Technical Solution

In one exemplary embodiment of the present disclosure, there is provideda VCM, the VCM comprising:

-   -   a base unit, a mover including a bobbin arranged at an upper        surface of the base unit and formed with a plurality of rotation        prevention units along a periphery and a first driving unit        arranged at a periphery of the bobbin, a stator including a yoke        configured to the base unit to surround the mover and inner yoke        units each extended to between the rotation prevention units,        and a second driving unit oppositely arranged to the first        driving unit, and an elastic member elastically supporting the        mover, wherein an object occurrence preventing portion is formed        between the rotation prevention unit and the inner yoke units to        decrease a contact area between the rotation prevention unit and        the inner yoke units.

Advantageous Effects

A VCM according to an exemplary embodiment of the present disclosure hasan advantageous effect in that a contact area between a rotationprevention unit of a bobbin and an inner yoke unit of a yoke contactingthe rotation prevention unit of the bobbin is reduced to decrease orinhibit generation of objects generated from the rotation preventionunit when the rotation prevention unit of the bobbin and the inner yokeunit are brought into contact, whereby quality degradation of an imageor a video can be prevented.

DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view illustrating a VCM according to anexemplary embodiment of the present disclosure.

FIG. 2 is an enlarged view of ‘A’ of FIG. 1.

FIG. 3 is a lateral view of a bobbin of FIG. 1.

FIG. 4 is a perspective view illustrating a bobbin according to anotherexemplary embodiment of the present disclosure.

BEST MODE

The disclosed exemplary embodiments and advantages thereof are bestunderstood by referring to the accompanying drawings. Like numbers referto like elements throughout. In the figures, certain layers, sizes,shapes, components or features may be exaggerated for clarity andconvenience.

Accordingly, the meaning of specific terms or words used in thespecification and claims should not be limited to the literal orcommonly employed sense, but should be construed or may be different inaccordance with the intention of a user or an operator and customaryusages. Therefore, the definition of the specific terms or words shouldbe based on the contents across the specification.

FIG. 1 is a cross-sectional view illustrating a VCM according to anexemplary embodiment of the present disclosure, FIG. 2 is an enlargedview of ‘A’ of FIG. 1, and FIG. 3 is a lateral view of a bobbin of FIG.1.

Referring to FIGS. 1, 2 and 3, a VCM (600) includes a base unit (100), amover (200), a stator (300), an elastic member (400) and an objectoccurrence preventing portion (500).

The base unit (100) takes a shape of a cubic plate, and is centrallyformed with a through hole (110) passing through an upper surface of thebase unit (100) and a bottom surface opposite to the upper surface. Eachof four corners formed on the upper surface of the base unit (100) iscoupled to a coupling pillar (120), where the coupling pillar (120) iscoupled to a spacer (330, described later). The mover (200) includes abobbin (210) and a first driving unit (220).

The bobbin (210) takes a shape of a cylinder opened at an upper surfaceand a bottom surface, and may be formed at an inner surface with afemale screw unit (212) for mounting at least one cylindrical lens. Thebobbin (210) is protrusively formed at a periphery (211) with aplurality of rotation prevention units (213) along the periphery (211)of the bobbin (210), where four rotation prevention units (213) may beformed along the periphery (211) of the bobbin (210), each spaced apartat a predetermined distance.

The rotation prevention units (213) prevent the rotation of the bobbin(210) by being hitched by an inner yoke portion (323) of a yoke (320,described later).

Although the exemplary embodiment of the present disclosure hasdescribed a plurality of rotation prevention units (213) protruded fromthe periphery (211) of the bobbin (210) each spaced apart at apredetermined distance, alternatively, it should be apparent that eachof the rotation prevention units (213) formed on the bobbin 210) maytake a recess shape concaved from the periphery (211) of the bobbin(210).

The first driving unit (220) is formed by winding a long wire insulatedby an insulating resin, and may be bonded to a surface of the rotationprevention unit (213) of the bobbin (210) using an adhesive. The stator(300) includes a second driving unit (310) and a yoke (320). Inaddition, the stator (300) may include a spacer (330).

In the exemplary embodiment of the present disclosure, the seconddriving unit (310) is arranged at an outside of the first driving unit(220). The second driving unit (310) is arranged opposite to the firstdriving unit (220). The second driving unit (310) includes four magnetsin a shape of a pillar, for example, and the four pillar-like magnetsare formed about the first driving unit (220), each spaced apart at apredetermined distance.

The yoke (320) is formed in a shape of a square plate, and includes ayoke upper plate (321) centrally formed with a round opening and yokelateral plates (322) extended from four edges of the yoke upper plate(321) to wrap the mover (100). Each of inner corners formed by a pair ofadjacent yoke lateral plates (322) is arranged with the second drivingunit (310). The yoke upper plate (321) is formed with an inner yoke unit(323) extended from the opening of the yoke upper plate (321) to therotation prevention units (213) of the bobbin (210).

The inner yoke unit (323) functions to prevent the bobbin (210) fromrotating by being contacted to the rotation prevention unit (213) in acase the bobbin (210) is rotated by leakage of electromagnetic fieldgenerated by the first driving unit (220) and turning effect generatedin a case a lens is mounted to the bobbin (210).

The elastic member (400) is arranged at a bottom surface of the bobbin(210) of the mover (200). In the exemplary embodiment of the presentinvention, the elastic member (400) may be formed in a pair, and each ofthe elastic members (400) is electrically insulated. The pair of elasticmembers (400) includes an inner elastic unit (410), an outer elasticunit (420) and a connection elastic unit (430).

The outer elastic unit (420), when seen in a top plan view, takes ashape of a bent strip, and is coupled to the coupling pillar (120) bybeing inserted into a pair of adjacent coupling pillars (120) of thebase unit (100). The inner elastic unit (410) is arranged at a bottomsurface of the bobbin (210). Thus, the inner elastic unit (410) takes ashape of a curved strip similar in shape to the bottom surface of thebobbin (210). The connection elastic unit (430), when seen in a top planview, is formed in a zigzag shape to be connected to the inner and outerelastic units (410, 420).

Referring to FIG. 1 again, an upper surface opposite to the bottomsurface of the bobbin (210) is arranged with an additional elasticmember (450) elastically supporting the bobbin (210). The spacer (330)serves to fix the elastic member (400), the additional elastic member(450), the mover (200) and the stator (300). The spacer (330) includesan upper spacer (332) and a bottom spacer (335), where the upper andbottom spacers (332, 335) are meshed. The bottom spacer (335) is coupledto the coupling pillars (120) of the base unit (100). The outer elasticunit (420) of the elastic member (400) is fixed between the bottomspacer (335) and an upper surface of the base unit (100), and theadditional elastic member (450) is fixed to a bottom surface of theupper spacer (332).

A cover (550) includes a cover upper plate (560) formed in a shape of asquare plate having a round opening for exposing a lens and a coverlateral plate (570) extended from an edge of the cover upper plate(560). The cover lateral plate (570) is coupled to the base unit (100).

Referring to FIGS. 2 and 3, the bobbin (210) is applied with a turningeffect in a case a lens is coupled to the bobbin (210), or the bobbin(210) vertically moves, and the bobbin (210) is horizontally rotated bythe turning effect applied to the bobbin (210). At this time, in a casethe bobbin (210) is rotated, the elastic member (400) and the additionalelastic member (450) are deformed or twisted to twist an optical axis ofthe mover (200) or to generate a driving defect of the mover (200).

As noted from the foregoing, the rotation of bobbin (210) is preventedby the rotation prevention unit (213) formed at the periphery of thebobbin (210) and the inner yoke unit (323) of the yoke (320), where, ina case the inner yoke unit (323) and the rotation prevention unit (213)are brought into contact, a fine objects may be generated from thebobbin (210) which is a molded material, and the fine objects may dropto be introduced to an upper surface of an IR (Infrared) filter arrangedat a rear surface of the base unit (100).

In a case the fine objects generated from the bobbin (210) areintroduced to an upper surface of an IR (Infrared) filter, there may begenerated a quality degradation of a digital image or a video due to thefine objects.

In the exemplary embodiment of the present disclosure, the VCM (600)includes the object occurrence preventing portions (500) preventinggeneration of objects by contact between the rotation prevention unit(213) of the bobbin (210) and the inner yoke unit (323) of the yoke(320). The object occurrence preventing portions (500) reduce orinhibit, for example, a generated amount of fine objects from therotation prevention unit (213) by reducing a contact area between therotation prevention unit (213) of the bobbin (210) and the inner yokeunit (3230 of the yoke (320). The object occurrence preventing portion(500) is formed at each lateral surface (213 a) of the rotationprevention unit (213) opposite to both lateral surfaces of the inneryoke unit (323) and contacting the inner yoke unit (323).

Particularly, the object occurrence preventing portion (500) formed onthe lateral surfaces (213 a) opposite to both lateral surfaces of theinner yoke unit (323) is formed in a shape of a staircase extendedoutwardly from the rotation prevention unit (213) for reducing thegenerated amount of fine objects from the rotation prevention unit(213).

To be more specific, in a case the both lateral surfaces of the inneryoke unit (323) are formed in a shape of a straight line, a first gap isformed between the lateral surfaces of the rotation prevention unit(213) and the lateral surfaces of the inner yoke unit (323), and asecond gap greater than the first gap is formed between the lateralsurfaces of the object occurrence preventing portion (500) and the inneryoke unit (323).

Hence, in a case the bobbin (210) is rotated, the lateral surfaces ofthe inner yoke unit (323) are brought into contact with each lateralsurface (213 a) of the area-reduced rotation prevention unit (213),whereby the generated amount of objects can be reduced or inhibited bythe rotation prevention unit (213). Furthermore, in view of the factthat the bobbin (210) is injection-molded, the object occurrencepreventing portion (500) may be formed at a predetermined depth from anupper surface of the bobbin (210).

Meanwhile, in a case the object occurrence preventing portion (500) isformed using an injection molding method, albeit being difficult, theobject occurrence preventing portion (500) may be intermittently formedwith at least two rotation prevention units (213) in order to reduce acontact area between the rotation prevention unit (213) of the bobbin(210) and the inner yoke unit (323).

Now, referring to FIG. 4, even if the amount of objects generated bycontact between the rotation prevention unit (213) and the inner yokeunit (323) in response to the rotation of bobbin (210) may be reduced orinhibited by the object occurrence preventing portion (500), a smallamount of objects can be generated, such that, in the exemplaryembodiment of the present disclosure, an object collecting member (590)may be formed at a floor surface of a groove formed by the rotationprevention unit (213) in order to prevent a small amount of objectsgenerated from the rotation prevention unit (213) from entering the IRfilter.

The object collecting member (590) may include a synthetic resin, forexample, having a sufficient viscosity for collecting the foreignobjects. The object collecting member (590) may include an epoxy resinhaving a viscosity.

Although the exemplary embodiment of the present disclosure hasdescribed and explained the reduction or inhibition of fine objects ofthe rotation prevention unit (213) of the bobbin (210) by forming arecess-shaped object occurrence preventing portion (500) on the rotationprevention unit (213) of the bobbin (210), alternatively, a portion ofthe inner yoke unit (323) of the yoke (320) opposite to the rotationprevention unit (213) may be cut to reduce a contact area with therotation prevention unit (213). Furthermore, in a case an objectoccurrence preventing portion is formed at a lateral surface of theinner yoke unit (323), a plurality of object occurrence preventingportions may be intermittently formed along the lateral surface of theinner yoke unit (323).

As apparent from the foregoing, a contact area between a rotationprevention unit of a bobbin and an inner yoke unit of a yoke contactingthe rotation prevention unit of the bobbin is reduced to decrease orinhibit generation of objects generated from the rotation preventionunit when the rotation prevention unit of the bobbin and the inner yokeunit are brought into contact, whereby quality degradation of an imageor a video can be prevented.

The previous description of the present disclosure is provided to enableany person skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to limit theexamples described herein, but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

The invention claimed is:
 1. A Voice Coil Motor (VCM) comprising: abase; a mover including a bobbin disposed on the base and formed with aplurality of rotation prevention units provided on a periphery of thebobbin and a first driving unit arranged at the plurality of rotationprevention units of the bobbin, wherein the plurality of rotationprevention units protrudes from the periphery of the bobbin; a statorincluding a yoke configured to surround the mover and including inneryoke units each extending to between the rotation prevention units, anda second driving unit oppositely arranged to the first driving unit; andan elastic member arranged on an upper surface of the bobbin andsupporting the bobbin, wherein the rotation prevention unit comprises alateral surface contacting with the inner yoke unit when the bobbin isrotated and an upper area connecting with the lateral surface, wherein agap is formed between the upper area of the rotation prevention unit andthe upper surface of the bobbin to decrease a contact area between therotation prevention unit and the inner yoke units, wherein a lateralsurface of the inner yoke unit comprises a first portion correspondingto the gap and a second portion facing the rotation prevention unit, andwherein when the bobbin is rotated, the second portion of the lateralsurface of the inner yoke unit is configured to be brought into contactwith the rotation prevention unit and the first portion of the lateralsurface of the inner yoke unit does not contact with the rotationprevention unit, and wherein the first driving unit includes any one ofa coil and a magnet, and the second driving unit includes any remainingone of the coil and the magnet.
 2. The VCM of claim 1, wherein the gapis formed by a groove formed at the lateral surface of the rotationprevention unit opposite to the lateral surface of the inner yoke unit,and wherein the rotation prevention unit comprises a staircase shape. 3.The VCM of claim 2, wherein a first gap is formed between the lateralsurface of the rotation prevention unit and the second portion of thelateral surface of the inner yoke unit in a horizontal direction, and asecond gap greater than the first gap is formed between a surface of thegroove facing the first portion of the lateral surface of the inner yokeunit in the horizontal direction.
 4. The VCM of claim 1, furthercomprising an object collecting member at a floor surface of the grooveof the rotation prevention unit, and wherein the object collectingmember includes an epoxy resin having a viscosity.
 5. The VCM of claim1, wherein the inner yoke unit comprises a groove formed at the lateralsurface of the inner yoke unit to decrease a contact area between therotation prevention unit and the lateral surface of the inner yoke unit.6. The VCM of claim 1, wherein the first portion of the lateral surfaceof the inner yoke unit is disposed on a same plane as the second portionof the lateral surface of the inner yoke unit.
 7. The VCM of claim 1,wherein the plurality of rotation prevention units comprises fourrotation prevention units and the inner yoke units comprise four inneryoke units.
 8. A Voice Coil Motor (VCM) comprising: a stator including ayoke and a magnet disposed on the yoke, wherein the yoke comprises anupper plate, a lateral plate extending from the upper plate, and aninner yoke unit extending from the upper plate; a mover including abobbin formed with a rotation prevention unit and a coil disposed on therotation prevention unit of the bobbin, wherein the rotation preventionunit protrudes from a side surface of the bobbin; an elastic memberarranged on an upper surface of the bobbin and supporting the bobbin;and a base disposed below the mover; wherein the rotation preventionunit comprises a lateral surface configured to be brought into contactwith the inner yoke unit when the bobbin is rotated and an upper areaextending from the lateral surface, wherein the upper area of therotation prevention unit is spaced apart from the upper surface of thebobbin in an optical axis direction to decrease a contact area betweenthe rotation prevention unit and the inner yoke unit.
 9. The VCM ofclaim 8, wherein a lateral surface of the inner yoke unit comprises afirst portion corresponding to a space between the upper surface of thebobbin and the upper area of the rotation prevention unit, and the firstportion of the lateral surface of the inner yoke unit does not contactwith the lateral surface of the rotation prevention unit.
 10. The VCM ofclaim 9, wherein the lateral surface of the inner yoke unit furthercomprises a second portion facing the lateral surface of the rotationprevention unit, and the second portion of the lateral surface of theinner yoke unit is configured to be brought into contact with thelateral surface of the rotation prevention unit when the bobbin isrotated.
 11. The VCM of claim 10, wherein the second portion of thelateral surface of the inner yoke unit is disposed below the firstportion of the lateral surface of the inner yoke unit.
 12. The VCM ofclaim 11, wherein in the optical axis direction, a length of the lateralsurface of the rotation prevention unit is longer than a length of thefirst portion of the inner yoke unit corresponding to the space betweenthe upper surface of the bobbin and the upper area of the rotationprevention unit.
 13. The VCM of claim 11, wherein the second portion ofthe lateral surface of the inner yoke unit is disposed on the same planeas the first portion of the lateral surface of the inner yoke unit. 14.The VCM of claim 8, wherein a protrusion protrudes from the uppersurface of the bobbin, and the elastic member comprises a shapecorresponding to the protrusion of the bobbin.
 15. The VCM of claim 8,wherein the inner yoke unit comprises a first inner yoke unit, a secondinner yoke unit spaced apart from the first inner yoke unit, a thirdinner yoke unit disposed opposite to the first inner yoke unit and afourth inner yoke unit disposed opposite to the second inner yoke unit,wherein the rotation prevention unit comprises a first rotationprevention unit disposed between the first inner yoke unit and thesecond inner yoke unit and a second rotation prevention unit disposedbetween the second inner yoke unit and the third inner yoke unit, thethird rotation prevention unit disposed between the third inner yokeunit and the fourth inner yoke unit, and the fourth rotation preventionunit disposed between the fourth inner yoke unit and the first inneryoke unit.
 16. The VCM of claim 15, wherein the first inner yoke unitcomprises a first lateral surface facing the first rotation preventionunit and a second lateral surface opposite to the first lateral surfaceand facing the fourth rotation prevention unit, wherein the firstlateral surface of the first inner yoke unit is parallel to the secondlateral surface of the first inner yoke unit, wherein the first lateralsurface of the first inner yoke unit comprises a first portioncorresponding to a space between the upper surface of the bobbin and theupper area of the first rotation prevention unit in the optical axisdirection and a second portion facing the lateral surface of the firstrotation prevention unit in a direction perpendicular to the opticalaxis direction and disposed below the first portion of the first lateralsurface of the first inner yoke unit, and wherein when the secondportion of the first lateral surface of the first inner yoke unitcontacts the first rotation prevention unit of the bobbin, the firstportion of the first lateral surface of the first inner yoke unit isconfigured not to contact the first rotation prevention unit of thebobbin.
 17. The VCM of claim 16, wherein the second lateral surface ofthe first inner yoke unit comprises a first portion corresponding to aspace between the upper surface of the bobbin and the upper area of thefourth rotation prevention unit in the optical axis and a second portionfacing the lateral surface of the fourth rotation prevention unit in thedirection perpendicular to the optical axis direction and disposed belowthe first portion of the second lateral surface of the first inner yokeunit, and wherein when the second portion of the second lateral surfaceof the first inner yoke unit contacts the fourth rotation preventionunit of the bobbin, the first portion of the second lateral surface ofthe first inner yoke unit is configured not to contact the fourthrotation prevention unit of the bobbin.
 18. The VCM of claim 8, whereinthe rotation prevention unit of the bobbin is configured to be hitchedby the inner yoke unit to prevent rotation of the bobbin.
 19. The VCM ofclaim 8, further comprising a cover surrounding the stator and the moverand coupled to the base.
 20. A camera module comprising: the VCM ofclaim 8; a lens coupled to the bobbin; and an image sensor, wherein thebobbin comprises a screw unit for coupling the lens.